Process of manufacturing lubricating oils



Patented Feb. 3, 1942 PROCESS OF MANUFACTURING LUBRICATING OILS Eddie M. Dons and Oswald G. Mauro, Tulsa, Okla., assignors to Mid-Continent Petroleum Corporation, Tulsa, Okla., a corporation of Delaware No Drawing.

1 Claim.

This invention relates to processes of manufacturing lubricating oils, and more particularly to the extraction of naphthenic and aromatic components of lubricating oil stocks.

Prior to this invention; various selective solvents have been employed. to extract naphthenic and. aromatic compounds from the paraffinic constituents of lubricatingoil stocks, and some of these old processes are quite satisfactor when employed within limited temperature ranges to extract the undesirable constituents of a limited number of stocks. For example, some of the old selective solvents have a high efficiency when employed at low temperatures to refine non-viscous stocks, but lack the desired efiiciency When used at high temperatures, or when employed to refine wax-bearing oils and other viscous stocks. Other types of selective solvents can be effectively employed to refine the wax-bearing or viscous stocks, while lacking such efliciency when used with the non-viscous stocks. In a case where the refiner intends to extract only one stock, or a limited variety of stocks of approximately the same type, satisfactory results ma be obtained by adopting one of the old processes wherein the solvent has properties required for efiicient treatment of the similar stocks. However, where numerous very diiferent stocks are to be refined, the usual problem appears in considering the expense of employing a plurality of difierent processes, or in finding a process having the expected efficiency for the largest quantity of stock, while lacking the extractive properties desired for a smaller portion of the stock.

An object of the present invention is to overcome this old problem by producing a commercially feasible extracting process, wherein the selective solvent has the properties desired for nu-. merous different types of lubricating oil stocks, thereby eliminating the trouble and expense of employing a plurality of different extracting systems, and at the same time providing the desired efficiency and economy in refining the substantially different kinds of oils.

More specifically stated, we have found that the naphthenic and aromatic constituents of lubricating oils of every difierentstock types are readily soluble in Z-pentanone, 4-hydroxy, 4- methyl over a wide range of temperatures, while the parafiinic hydrocarbon constituents of these same lubricating oil stocks are negligibly soluble in said solvent within the temperature ranges wherein naphthenic and aromatic constituents are readily soluble. The considerable breadthof temperature ranges over which selective separa- Application March 25, 1940, Serial No. 325,812

tion is obtainable renders this solvent of particular value for the selective refining by solvent extraction of wax-bearin and other viscous I stocks, and an outstandin feature appears in the flexibility or universality of the process which provides for the desired high efficiency in refining the various different kinds of stocks.

The selectivity of Z-pentanone, 4-hydroxy, lmethyl is very great at temperatures between 110 F. and 130 F., within the fluid range of viscous oils, and this selectivity i not greatly im paired at the higher and lower temperatures. In fact, this solvent is efiective at 60 F. and also at higher temperatures up to about 200 F. It can be used'instead of one of the most desirable solvents for non-viscous stocks, and also employed with corresponding economy and efficiency in refining the other lubricating oil stocks likel to be extracted in a petroleum oil refinery.

Furthermore, the selectivity and other characteristics of 2-pentanone, 4-hydroxy, -methyl can be readily controlled and varied by the addition of other solvents including the ethylene and propylene glycols, and certain acetates, alcohols, or the like.

For example, to provide for an increase in the extracting temperature without substantially modifying the selective properties, one may add monoethylene glycol, diethylene glycol, triethylene glycol, or propylene glycol. On the other hand, to provide for a decrease in the extracting temperature, without substantially modifying the selective properties, one may add ethyl acetate, propyl alcohol, ethyl methyl ketone, butyl alcohol, isopropyl acetate, or acetone. It will be observed that such addition agents provide for convenient variations in numerous conditions, which add to the flexibility or universality of the process.

In commercial practice, the extracting process may be carried out in a continuous countercurrent system, a batch system, or in any other suitable extracting apparatus. The solvent comprising z-pentanone, 4-hydroxy, e-methyl, or its equivalent, is mixed with the lubricatin oil stock, so as to dissolve the naphthenic and aro matic components of said stock in the solvent. The resultant naphthenic'solution is then separated from the more'parafiinic constituents of said lubricating oil stock. Thereafter, this solutiton is preferably distilled to separate the solvent from the oil. The paraflinic solution may be likewise distilled to remove the relatively small percentage of solvent carried thereby.

It will also be understood that the 2-pentanone, 4-hydroxy, 4-methyl may be used alone, or in combination with any of the above-mentioned addition agents. to modify the selective properties of the main solvent, or to provide for special variations in the extracting temperatures.

We claim:

In the art of extracting naphthenic compounds from lubricating oil stocks, the method which comprises mixing a lubricating oil stock with a 

